Some embodiments described herein relate to electromagnetic machines and more particularly to devices and methods for removably coupling a magnetic pole assembly and a backing member to a support structure of a rotor element.
Permanent magnet electromagnetic machines (referred to as “permanent magnet machines” or “electromagnetic machines” herein) utilize magnetic flux from permanent magnets to convert mechanical energy to electrical energy or vice versa. Various types of permanent magnet machines are known, including axial flux machines, radial flux machines, and transverse flux machines, in which one component rotates about an axis or translates along an axis, either in a single direction or in two directions (e.g., reciprocating, with respect to another component). Such machines typically include windings to carry electric current through coils that interact with the flux from the magnets through relative movement between the magnets and the windings. In a common industrial application arrangement, the permanent magnets are mounted for movement (e.g., on a rotor or otherwise moving part) and the windings are mounted on a stationary part (e.g., on a stator or the like). Other configurations, typical for low power, inexpensive machines operated from a direct current source where the magnets are stationary and the machine's windings are part of the rotor (energized by a device known as a “commutator” with “brushes”) are clearly also available, but will not be discussed in detail in the following text in the interest of brevity.
In an electric motor, for example, current is applied to the windings in the stator, causing the magnets (and therefore the rotor) to move relative to the windings, thus converting electrical energy into mechanical energy. In a generator, application of an external force to the generator's rotor causes the magnets to move relative to the windings, and the resulting generated voltage causes current to flow through the windings-thus converting mechanical energy into electrical energy.
Surface mounted permanent magnet machines are a class of permanent magnet machines in which the magnets are typically mounted on a ferromagnetic structure, or backing, commonly referred to as a back iron. In some such machines, multiple magnetic pole assemblies are permanently affixed or otherwise attached to the back iron in a manner that may not allow for easy and/or efficient removal of, for example, a single magnetic pole assembly, if needed. For example, if a magnetic pole assembly no longer functions at a sufficient level, it may be desirable to remove and replace that magnetic pole assembly without having to remove a larger section of the machine.
Further, in some such machines, the handling of components that have significant attractive and/or repulsive forces to the magnet pole assembly and/or to the support structure (e.g., the back iron) can be challenging. Such magnetic forces can be difficult to control, as they typically increase as the components are brought closer together, and may cause deflection in unfavorable directions.
Thus, a need exists for improved apparatus and methods to couple a magnetic pole assembly to a support structure of an electromagnetic machine (e.g., a permanent magnet machine) to aid in the magnetization, handling and servicing of the electromagnetic machine.